Question

I am trying to pass a mysqli connection to a class for it to use prepared statements. However, I am missing something and it is not working. What a i doing wrong?

The following code outputs “no”

index.php

$db_host = 'localhost';
$db_name = 'my_database';
$db_user = 'my_user';
$db_password = 'my_password';

$con = new mysqli($db_host,$db_user,$db_password,$db_name);
if (mysqli_connect_errno())
{
    die(mysqli_connect_error()); 
}

$obj = new Obj( $con );

obj.php

Class Obj
{
    public function __construct( mysqli $con )
    {
        $sql = "SELECT * FOM myTable";
        if($con->prepare( $sql ))
        {
            echo "yes";
        }
        else
        {
            echo "no";
        }        
    }
}

Answer 1

If you had failed to pass a mysqli connection to your class, you’d be getting a fatal error on this line:

public function __construct( mysqli $con )
                             ^^^^^^

But not only the constructor starts running fine, you can even access a class method:

if($con->prepare( $sql ))

To sum up, all that happens is that mysqli::prepare() returns false because there was an error while preparing the SQL statement. I’m not familiar with mysql but you can probably get the exact error message with mysqli::$error_list or mysqli::$error:

    if($con->prepare( $slq ))
    {
        echo "yes";
    }
    else
    {
        echo "no: " . $con->error;
    } 

If SELECT * FOM myTable is the actual query, I suppose it’s a simple syntax error since you’ve misspelt FROM.